1. Technical Field of the Invention
The present invention relates to a laser protective wall comprising at least one metallic surface-treated thin sheet metal wall.
2. Prior Art
From DE 196 29 037 C1, laser protective walls are known that serve to shield laser work stations, especially against high-power metal-working lasers, in such a way that the protective walls comprise parallel, spaced-apart sheets of metal, the surfaces of which that face the laser are provided with a light-absorbing coating. The metal sheets are held in place by a framework structure within which the metal sheets are designed self-supporting, which, depending on the size of the wall, necessitates a considerable thickness of the sheet metal. Experiments have shown that the absorbing color coat, in particular also a graphite coating, hardly presents a significant obstacle for a laser beam.
It is the aim of the invention to reveal a significantly more effective laser protective wall with the same or a lesser wall thickness.
This aim is met in such a way that the metallic walls are made of anodized or chromalized light metal.
Surprisingly, extensive experiments have shown that an anodized coating or chromalized coating on a light metal part produces a substantial increase in the burn-in and burn-through times of a laser beam and, with a low-energy laser beam, or a laser beam that has been weakened by dispersion, prevents a penetration of the beam altogether. Furthermore, an anodized coating on the exit side increases the dispersion of a penetrated laser beam, so that its penetration power at a subsequent wall is weakened accordingly.
The framework structure that frames and/or laterally supports the metallic sheet metal walls is preferably also made of anodized light metal. A light metal profile material has proven suitable that has many differently angled interior webs and interspersed hollow spaces. Into these, connecting elements can be inserted, which are held in a removable manner by means of a snap-in connection, if the outer walls have grooves that expand towards the inside. Grooves of this type are preferably provided on all sides, so that it is also possible to form corners with multi-layered sheet metal walls on the support profiles.
Furthermore, a wall construction will be revealed that is simpler and more variably adaptable to different work environments.
This wall is formed of extruded light metal profiles that are closely lined up side-by-side, of which a wall or at least a continuous partial wall is assembled of lined-up light metal hollow profiles, which are designed with multi-staggered, thin-walled, multi-angled interior structures while leaving most of the intermediary hollow spaces.
Comprehensive experiments have shown that a weakening of the area-specific beam intensity hardly ever occurs in the interior of a metal sheet but particularly on the given exit side of a penetrated sheet metal wall, due to a divergent widening of the beam.
The novel protective wall can be used successfully especially if the protective wall must be arranged close to the laser focus where, for example, a 4 kW laser has a diameter of 0.4 mm. If only a partial wall is constructed of the hollow profile elements, and if their respective joint areas are bridged, the multi-angled interior structures produce four or more walls in each direction, through which a penetrating beam is dispersed on the respective exit sides until it is weakened to the point that it no longer has any penetration power.
The individual hollow profile elements and exterior flat profile elements are assembled as needed, with overlapping joints. Multiple layers of hollow profile elements may be arranged one behind the other, if required, and the exterior surfaces are lined with the flat profile sheets.
The individual profile elements are provided with joints that expand toward the inside, which are located opposite one another when the profile elements are arranged side-by-side and/or offset one behind the other. Form-fit tongue-profile strips are then inserted into the joints when a connection is to be made. The tongue-profile strips may also be integral, in which case the respective grooves and tongues are formed complementary, which permits a problem-free side-by-side alignment and arrangement in layers one behind the other.
The exterior flat profile elements are preferably provided with bracing spring strips, which are pushed into the grooves of the hollow profiles where they interlock in a removable manner.
A beam-dispersing space is also formed between the flat profile element and the hollow profile element, since a spacer, which is supported on the hollow profile, is formed at the end of each flat profile.
The individual hollow profiles are preferably substantially rectangular on the outside and have a height-width ratio of 1 to 2, so that a nested wall construction with a constant thickness can also be accomplished without special profiles in square wall corners. This method of construction is assisted by the fact that the grooves on the short profile sides have the same distance from the corner as the grooves on the long sides of the profile.